1. Field of the Invention
The present invention is directed to an attitudinal control apparatus for an airborne or water borne vehicle and, in particular, an apparatus for actuating a control surface of such vehicles.
2. Description of the Related Art
Airborne or water borne vehicles are often used to deliver a payload to a target location or to carry a payload over a desired area. For example, projectiles may be used in combat situations to deliver a payload, such as an explosive warhead or a kinetic energy penetrator to a target to disable or destroy the target. Surveillance vehicles may carry a payload designed to sense certain conditions surrounding the vehicle, such as objects on the ground or weather activity. Such vehicles typically include a plurality of control surfaces, such as fins, canards, flares, flaps, tabs, etc., that are articulated to control the vehicle's direction and attitude as it moves through an atmosphere or liquid.
In many conventional vehicles, a separate actuation apparatus (e.g., a motor and a power transmission system) is provided for each of the control surfaces. For example, if a projectile includes four fins, four separate motor and power transmission assemblies would be provided. In such vehicles, one or more computers determine the desired attitude components (i.e., pitch, yaw, and roll) of the vehicle depending upon its destination, direction of travel, obstacles in its path, and other factors. The computer or computers then calculate the required orientation of the control surfaces to attain the desired vehicle attitude and command each of the actuation apparatuses separately to orient the control surfaces accordingly.
It is generally desirable, however, for such vehicles to be lighter in weight, rather than heavier, so that their ranges may be extended while using an equivalent amount of propellant. Further, it is generally desirable for the contents of the vehicle other than the payload, e.g., the motors, power transmission assemblies, and the like, to be more compact, so that larger payloads may be used within the body of the projectile. It is also often desirable to decrease the complexity of calculating the required orientation of the control surfaces to attain the desired vehicle orientation and commanding the actuation apparatuses to orient the control surfaces accordingly.
The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above.